Đáp án:
Giải thích các bước giải:
$\text{a)(x-5)²-(x-5)(x+2)=0}$
$\text{⇔(x-5)(x-5)-(x-5)(x+2)}$
$\text{⇔(x-5)(x-5-x-2)}$
$\text{⇔(x-5)-7=0}$
$\text{⇔\(\left[ \begin{array}{l}x-5=0\\-7=0\end{array} \right.\) }$
$\text{⇔\(\left[ \begin{array}{l}x=5\\x=0\end{array} \right.\) }$
$\text{b)x(x+2)-(2+x)=0}$
$\text{x(x-2)-(x+2)=0}$
$\text{⇔(x+2)(x+1)=0}$
$\text{⇔\(\left[ \begin{array}{l}x+2=0\\x+1=0\end{array} \right.\) }$
$\text{⇔\(\left[ \begin{array}{l}x=-2\\x=1\end{array} \right.\) }$
